SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7136a426b4c7952f5bf1498c732894ab5ab39d81f734a3772010be18e3855d47' 
  AND token = 'Fl1Qvnh2LqjTX8Zr0tmcMHT3a+6EKdOTjUJa+92OFAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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