SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3310a98ef3d54927b256176efb068e34062ee90c2cdeb5ffe44ea733758b1f5' 
  AND token = 'xZlzBJf+KCHhFfR13u4mCjIj/nE30347twS9StKg0/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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