SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cbe825eb913673fc0b58d35e0f874231b7fbb339a74ee17e946b81b0b7cee50' 
  AND token = '3ZOFlNrpbtdYQ1PbWI/Ha3KecetmG/7VM7rjl5E5/80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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