SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c8a26e329bad903f7269768193fee4273e4bcd67008c0305816f20cf1aa3719' 
  AND token = 'Phfk7TRJ2fb/YqDieFoJnHunwyfjSP+TeJUwtAnoVWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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