SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a44693a9fdaff3d370999d60f8c4d099b874f376e956dc32cceedf51434a83a' 
  AND token = 'E3AUOfwjrMvjXfXjAvbyZfIQEKkzNVo0IjPAzDQAVWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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