SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8397fde318d4f1f98cefa73bb13d320aad7a48618545bc4be7815bab21206a02' 
  AND token = 'C+YTNACKMv1vbjoWYROmK1xkoJDuSu7TE5V3Gv83xmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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