SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1839aeb3265f111ca78357f454684c4244da56d6fde3623d1607e154c99c3ef' 
  AND token = 'lax30sKN5bxS7gLgODLdlkXR4VM0zXWbdu2wdKP2Gao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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