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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6dfd1dd995c7a9ab3fa4d41a8ce336182c907bc4011e197da7a6dcd3a70ce1c' 
  AND token = 'm5IcdzeT/+fqgIEtbpIlM8GUeRXEOUf8YMBdy7KHwAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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