SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5f9dc75deb1a983d08c2a12bed6ec2e573b3c58fe6445b35c55eb2b8f1a792c' 
  AND token = 'HpOL9TQFFRYaC+PzfN/jQ8o2LAFILsnlZyrM4dmRLJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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