SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8e668cd78607784f791a50221c3191bd97f2b0c43ac56877e474b9d2004fc76' 
  AND token = 'aQ1KwXbQ9/vwR/LwhdwhXVETO4TzONgZtzu57i3Y+/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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