SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '814b2112e483a3a3e48edae8749f77427c024ec37db7137a6d04a62fb9d2b7b9' 
  AND token = 'mG0YITbccMzQZKmZ5XXWqPI4OKmMoXzX1oIdVnlqUWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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