SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc9a9ce0064afd9d1063e11dac39dd5c05144e71591bf5f6b5bfec9455f72bd1' 
  AND token = '6qzxcwi8ELxpOmWI8cLD7eJLnQEUDmEaibIS945cSlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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