SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8efe4b66ce1035ea9a4109992ee8845875542ee7b0f0c05a538d04e969c9360d' 
  AND token = 'jXlmFDAfDrnoHOvEc3CgslxXcBdjwOIvY/qmWINXI0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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