SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9255b571dce1c25ea55ec1778930f050bddeb8364d2679b31df5c908e23b3025' 
  AND token = '+sgDnnmrhgyyWtbGUKO1rkODSHiIC7kYAVkXVx+DfvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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