SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bc88787668d03734dc5b0731695d364297d24e5a572b0f0f148e725bef24164' 
  AND token = '4/gNHfh0/kmuq1GvdZlwYBOd45UEJmbB1Ngi/2EqVR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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