SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b10e9124760592beb20372e4d02b0acc41a8989260379de6f61f2e1888be35b' 
  AND token = 'JFlx9SdkwZWCtAil1CJGmRuRg24FyrWFKOwIH7cRH9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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