SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70dc36f98e7470fb352142f676f752b3acd1853b5f998d2e8538a3b6eea2c57a' 
  AND token = 'MNxZZ/0OaL6cTSUmVGT9kQvYLDr0pyRFDVUMuzyJ/mI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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