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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de6bb7fc5350ebc7cc5e72366b141bd03fe7b161def0a20f7f0f562ab8ab5923' 
  AND token = 'lQFD0aU8FFLJDYFFRvwjBBgzI57/CTeYVF/U5U7tYhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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