SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14938b953408d87eaf238d97539c3dbad0d68825b6a38ea14a773605a5c44f62' 
  AND token = 'eWwCA2OIZJipsOCnIE8JqLviVjHzV3zKIVjjqEYpiYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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