SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7519ad1518e4efed067fad4643e8428ce97dd6361b7447adf5d9040c1a674377' 
  AND token = 'r3LIOZc96HpAR55LDqVS8nry8bg/xcHE2vDqBNcsTyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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