SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f711b3800bdbdd5302e24990198d902b995e70500bb54970fbf8cc2ba0ac7b2' 
  AND token = 'hqDVyZCinej8NShMz1kRYXAClPzT+7rzpcW+w1/EIvM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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