SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5690c68bd32de108f20e43c9b8a1dfeee3790d88da999448aff95dbcdf51b1d9' 
  AND token = '7DAyu4jawy42mWsPsLdMuf+pYDt7OfmOukWjgO/TKWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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