SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '915824600b6325bda4d0c38bae6592f8b3a3657c4a34edab4c1d08e7a6c2be83' 
  AND token = 'rEAVPXD8Etb/l8N5dqdubqMQkyi30CIsCvpBRqyKQSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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