SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '4e44f11157a00136db1d256235d685f7340a05b3d3269cea4d978e666c1cf638' 
  AND token = 'ZbZNBzj+dg4/ft6tK3JODDpLRpl8RlNLWQmj2c+MLJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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