SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42a5febb158c0b5aac739fef913e0fb53edf204d5eeb1511d0cab6cd06faa32' 
  AND token = 'o/U6hrc11fluCK7TeYGijU7+aeI6WKCatsiW4syqaWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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