SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6b2d82ca2342eac9ca5e70679e4051262f9e0c0a0671120348cc7145f356dc1' 
  AND token = 'B5QMPDNwT88qWPQcsHhE85XCguN/zEXgNgFuPibfszo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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