SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f46ef836f840caf7c33bdf3a39de43a6ba5879bf0f478423a0cb437f4e2639b8' 
  AND token = '0SRcpgkSHWnZE6pSdjwajf5Xv4ZV0GqBQTWLwuRt/Js=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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