SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '950c417677499ae70b5820b416bf0521aca4181fd2eb69601883b81137d2f690' 
  AND token = '0a+RsBeObV4YTxxGqTaBGHDj6CRIb7vzVfMtCkDrhUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}