SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6302bacd73f452a0e79220803776f52587283ff841724352a8639f60b1b4048' 
  AND token = 'fuf1QPnrwSiLLVAsdnKYYsDhddJPLmiiwbaNUsyA6xc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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