SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8a4e384db08478cda874cda3f03864d2c0fa1313c567e157cd4d131788ea8ac' 
  AND token = 'sIo0h3UBHdHHoxWnpuqYgV+yuoTwlakktKjscfaLGhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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