SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7ac636db758dce550cb72725133d25004692e0778ffffbe88ec3717c5e980c3' 
  AND token = 'e/GxPNB/h92xPz8eMNcTLUjYgQCNoxS2VIn4SDdZ8/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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