SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5166634fdf42e2e2d38591299289c9c526aef08c5e340c848e25b64242ab5585' 
  AND token = 'ygp576VYE5ckNhykFrjT+WyII7zynYrqMi41uG8pdYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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