SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3c1ed691286ac92fe12e87284275796e9d0b2324e2f9348319eb9355303294e' 
  AND token = 'd9a999flCHY/rn8RhZKMen5ltjeU0DtRWkiNf6B6WmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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