SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8febb2cd590abe6a2046599c9137d984cfbd9235430986106f8b885fea0dab7' 
  AND token = 'uRhV5dnubUxXDmX6F2llpF5O6lIr1V34XiYGnovjBMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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