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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6f5fa6b3403dff321d5cd86e18acc69517bfbe53c472dc0f8253de970ad54ac' 
  AND token = 'G876TL5kcauc13dPb+RgMyq7NX6o2Gni0tXOzlUNk/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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