SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc2b3251aa30044a26c066b885df9a7e949f4a463aabb071e02308b48862d41d' 
  AND token = 'CCO5WKGNvFg/O4vcYM+nAhLWpVzxcmd4CHE/jzwTS2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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