SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b78f065f10eb7da333706af1b0252b8dbfcd6bd0fae907809092a599e0ecddeb' 
  AND token = 'Q72sY2CaCEAtjq+jxaarkcL11ifbv3v5MmMnet5nRSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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