SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afe483eb3a81470cd670dfd4aeb3d03fea60d0ddfed31d1dc4c15108938df1da' 
  AND token = '+kZhTnN3kkECzKqAeGGcoZjXbjRGYQr5FYuTTLI1nBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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