SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'edb707c17c2fee903371d3df1ec9d10cb3284393920061f6b471535fc5decef0' 
  AND token = 'PrF2z+N1mS0OHeFoJW7RTkp39bmaBUa90rogAynZHMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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