SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c76f0e656c3e0a1373d595b3855c54e83547a2810ac562eb970198f1e25637ef' 
  AND token = 'yuTACRa4LzB+BUncTcPzVzvJOklEyxu13SfVZBgOvRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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