SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55daa334e25108c93a6e3103a61ccd7b101c46ab07a0b04ae1cafcc015eb758b' 
  AND token = '5H5WCA7R1wJehZ/HqxtPoysqvGJ3kyjCBeSrF3AUErE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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