SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '635cd42990b1060821b88424f24b09038dfaf17c1a8904b554bba5f02d2baa18' 
  AND token = 'R1RBrf0uZNr8aL+fbgMuM46AwAMig69PvDvnXX2jMlE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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