SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '273af667dad844208e1505e4e2aa81e9237fdce2b973a4753e44bea5ad4d20ab' 
  AND token = 'nnzWhflUFQIKOTTBwRD+0fDCIIW1FANFEM0gVZ/EtZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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