SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b61d8bb22d02951f5edca831da031bc08d86a51cd2a3f54d68a93e8f1c27b4ac' 
  AND token = 'KZAgKsnDNp7cJNGrQudwNGDXdtuQDISqTLLFEM0wIv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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