SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8447bb6bfb7fc63cdfd57fce14b0b63fa3e1f914d00fb755acd9f539e5c72c87' 
  AND token = 'gLpCRZMIiFXs+57u2WuYk2uKVAsSfKYcNvfRZId2Wgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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