SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4640ed5c9657e71e862c33b586a2b11b91e4ee8c1f44c68ac3560f96f6037a12' 
  AND token = 'rrT+ohHRU/QtaKGxgZmVCswImqIEdjmktfzCpvX0Ehc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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