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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3afb9accf3ff70acc419eb7c1242bf017853e9a4b08df3b2f42ff8c20e66c3a' 
  AND token = 'Y/LDLpoWYCrF+Ee8hKLGiJNAhoJumUp9M7YtabKObQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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