SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a21e3c42dd4ad3cceceb27c298fc569110c00dbab430f5cdd7ffa7b476635e75' 
  AND token = 'Ty7b3rBAZaA1dGjzseBm9lbkaHCXjINzNwu0/YnjnnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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