SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c40769b38aabd99470450cda3b0e105b182165b896de1dace8c33d07ef51250' 
  AND token = 'nGRIGdsj9fRw9oJPU8z19nRynhwFPPBWBDX/V5+qfpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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