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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4ef0f42f4af609771bfaf5f9d54793e8dc5eecb7cb861fabcb75d025681bd4a' 
  AND token = 'JsS+pusLI0+AZoAqo/2r5nLdG2vqmD+zdqg59234GXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}