SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42acad217381367f470bf4096ef6a3ccce72829dce62a0a2bc9429aa4b569ecc' 
  AND token = 'JqVkr+eszyjuaJAoUhHRDuz34E3VbUU+rOU3lJgFp0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}