SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20e527bf2702157a64dc2e3df63aa62727f11c1fdb707f393784aeb093e231eb' 
  AND token = 'WUSvHiUGnSWEOS8z+Ux5TywjlwA1eGrywXMZ9A++H90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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