SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a88be19f7d3f6cf11a724fef761e44884b6aa4d323eceb5514899dded63787a0' 
  AND token = 'plj7OE2yBQaKiS23Avuh2XjQs6yPr6pBkMMdhfE2nC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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