SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '614e81fe927a92ea38a5fdca28899b63860230c59329bec592b1fd62697be720' 
  AND token = 'vbiHkLt14bEOxtlBhwk9AS3eqwkJeIlYnKZGUmndTI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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