SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a3eac367d8f817fb497ec980dcd13fdfd41b328411b17855bb566af9a2949f75' 
  AND token = 'CM/r4RA23K1jccfhwFpSS23LdPDfBgrDh6ljx6oKKro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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