SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ce82b143f7622d2be880759808b3843a96d2904c76fa5e4da471c09ab46682f' 
  AND token = 'hQjL11ywSMuGXDgqbuYlhBPztbHrfPXqN+dAYDGwi88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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